African-Americans and males compared to Whites and females, respectively, have a significantly higher prevalence of essential hypertension (EH) in the United States, particularly from young to middle adulthood. African- Americans and males have been found to exhibit exaggerated blood pressure responses to stress (i.e., reactivity) which has been postulated as one reason for their higher prevalence rates of EH. Recent adult findings suggest that enhanced total peripheral resistance responses may be the hemodynamic mechanism responsible for their exaggerated blood pressure reactivity. Little is known concerning the hemodynamic mechanisms responsible for blood pressure control (i.e., total peripheral resistance, cardiac output), in youth, particularly within the context of ethnicity and gender. Nor has research with youth assessed the predictive relationships between hemodynamic reactivity and changes in pathologic markers for the development of EH (i.e., resting blood pressure, left ventricular mass, and degree of concentric remodeling). This application will address these deficiencies in the understanding of hemodynamic reactivity in youth and its relationships to early markers of EH risk by following a biracial sample of 330 eight to 18 year olds for an additional five years. This project is an extension of a FIRST Award (12/01/88 - 11/30/93) in which this cohort, all of whom have positive family histories of EH, had their hemodynamic responses to a select set of laboratory stressors evaluated for four years. The specific aims of the research are to: Determine whether total peripheral resistance reactivity during childhood predicts changes in resting blood pressure, left ventricular mass and concentric remodeling up to eight years later after controlling for other expected predictors (i.e., age, gender, ethnicity, resting blood pressure, adiposity and ambulatory blood pressure). Determine the influence of ethnicity, gender and a select group of moderator variables (i.e., anger/hostility, physical activity, aerobic fitness, family environment) on children's total peripheral resistance reactivity to stress. Determine the stability over time and across stressors of children's hemodynamic reactivity to stress and stability of 24-hour ambulatory blood pressures. The long-term objectives of this project are to understand the development of children's hemodynamic reactivity, particularly total peripheral resistance, and its influence upon early pathobiologic markers of EH prior to manifestation of disease. This information may eventually be used to identify children who are at greatest risk for development of EH and foster the development of interventions that may prevent early onset of EH and improve health.